Comparative susceptibility of Anopheles subpictus from fresh and brackish water areas to Plasmodium falciparum infection.

Anopheles subpictus from fresh and brackish water areas were fed simultaneously, on five volunteers, with Plasmodium falciparum gametocytes in their blood. The susceptibility to infection was compared. Infections were found in both waters, but to different degrees. The mean susceptibility rate among fed mosquitoes was 6.1% from the fresh water area and 17.4% from the brackish water area. The mean number of oocysts in the former was 3.4 +/- 3.2 and 4.2 +/- 4.32 in the latter. The mortality rate, up to day 9 post feeding, was 93.8% in fresh water form and 90.1% in brackish water form. Dissections of wild caught females showed that longevity of adults from both areas was shorter, 7-8 days. Despite a considerable proportion of mosquitoes being anthropophilic and susceptible to infection, their low longevity seems to be the limiting factor in their role in malaria transmission in these areas.